Cycle question

[forked_horn]

First off, I'd like to introduce myself and say thank you all for the great information on this sight. I have been a lurker for quite a while and have had the pleasure of enjoying this hobby for 7 years and look forward to many years to come! About a year and a half ago my work took over and unfortunately my tank started going down hill with the availability of time. The final straw was when my DIY led light lost the white diodes. So it sat "dorment" covered in algae and aptasia with no fish up until about a month and a half ago. As time started to become more available for the forseeable future i decided it was time to start over again! I started by pulling all of the rock and letting it sit in a bleach bath for about a week. Wow did that stuff turn white! I vacuumed the sand bed as i drained the water. I then added about 100 more lbs of sand in varying grit or size on top of the existing sand (wanted a deeper bed). I returned the bleach rock to the tank after a vinegar dip and thorough rinse. I filled the tank up with fresh RODI water (no salt) and let it run for about 2 weeks. It appears as though the cycle started at that time as i could smell ammonia the first week. I then drained the fresh water and introduced some LR from a local tank and filled with new RODI salt water. Within a couple days diatoms started taking over (way sooner than i imagined). I started testing about a week in and found ammonia, nitrite and nitrate all to be undetectable. I proceeded to test every day for the next week without a rise in any level though i noticed a lot of bubbles coming from the sand bed. Against better judgement I added some chromies to see if things would change. NADA! Now im sitting here a week after adding the fish and the diatoms are starting to recede and there is still no detectable amounts of ammonia, nitrite, nitrate or phosphate.The fish seem healthy as can be! But it seems like I should have seen some levels. Is it possible that the tank could've cycled that fast from the old sand? Should i be preparing for the big bang?

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[mcgyvr]

Yep.. sounds like you had little to no cycle..
Just introducing live rock brings bacteria into the tank and may cause little to no cycle..

Just go slow/don't stock the tank like crazy and continue to monitor for a few more weeks just to make sure its cycled sufficiently..

 

[thegrun]

I agree, it sounds like the live rock you added had a sufficient amount of bacteria to prevent a new cycle, but as advised go very slowly with any new fish additions. I would wait at least two more weeks before adding more fish, and only one or two small fish at that time.

 

[forked_horn]

Thanks for the help! I will be sure to take it slow this time round.

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[scooter31707]

I agree. If it was me I would go with CUC first.